Heat exchanger with compound plates

Abstract

A heat exchanger for donating heat from one fluid stream to another fluid stream, comprising a plurality of compound heat exchanger plates, each plate having a corrugated heat exchange portion and a header portion which is not corrugated, the heat exchange portion being a separate component from the header portion, and being joined permanently to the header portion, respective plates being joined together to form heat exchanger cells. A heat exchanger plate may be formed in a method having the following steps: (a) forming a heat exchange portion, which is of corrugated cross section; (b) forming a header portion, which is not corrugated; and (c) joining the header portion permanently to the heat exchange portion to form a compound plate.

1 . A heat exchanger, for donating heat from one fluid stream to another fluid stream, comprising a plurality of compound heat exchanger plates, each plate having a corrugated heat exchange portion and a header portion which is not corrugated, the heat exchange portion being a separate component from the header portion, and being joined to the header portion.  
   
   
       2 . A heat exchanger as claimed in  claim 1 , in which respective pairs of compound plates are sealed to one another at their edges to define respective heat exchanger cells, respective cells being joined together by holes, formed in the header portion of the compound plates and sealed around their edges, such holes providing fluid inlets and/or outlets to each cell.  
   
   
       3 . A heat exchanger as claimed in  claim 1 , in which the header portion is substantially planar.  
   
   
       4 . A heat exchanger as claimed in  claim 1 , in which the material thickness of the header portion is greater than the material thickness of the corrugated heat exchange portion.  
   
   
       5 . A heat exchanger as claimed in  claim 1 , in which the portions of the compound plates are joined together by welding.  
   
   
       6 . A heat exchanger as claimed in  claim 1 , in which the portions of the compound plates are joined together by seam welding.  
   
   
       7 . A heat exchanger as claimed in clam  1 , in which the corrugations at an end of the heat exchange portion are crushed to the center line of the heat exchange portion, forming a planar surface to which the header portion is joined.  
   
   
       8 . A heat exchanger as claimed in  claim 1 , in which one side of the header portion has a plurality of projections.  
   
   
       9 . A heat exchanger as claimed in  claim 8 , in which the projections are ribs.  
   
   
       10 . A heat exchanger as claimed in  claim 8 , in which the projections are so arranged as to constitute flow guides.  
   
   
       11 . A heat exchanger as claimed in  claim 1 , in which each compound plate has two header portions, disposed at opposite ends of a heat exchange portion.  
   
   
       12 . A heat exchanger as claimed in  claim 11 , in which the corrugations of the heat exchange portion are pressed around their remaining edges, and respective pairs of compound plates are welded or otherwise fixed around their perimeters to form the said matrix of heat exchanger cells.  
   
   
       13 . A heat exchanger as claimed in  claim 1 , in which the fluid inlet hole into a respective cell is provided at one end of the matrix and the fluid outlet hole from the said cell is provided at the opposite end of the matrix.  
   
   
       14 . A heat exchanger as claimed in  claim 1 , in which the holes in the cells at one end of the matrix are staggered relative to the holes in the cells at the other end of the matrix.  
   
   
       15 . A heat exchanger as claimed in  claim 1 , in which the holes are elongated in a direction parallel to the corrugations.  
   
   
       16 . A heat exchanger as claimed in  claim 1 , in which the inlet holes are welded or otherwise fixed around their perimeters and/or the outlet holes are welded or otherwise fixed around their perimeters to join together adjacent cells.  
   
   
       17 . A heat exchanger as claimed in  claim 1 , in which heat is extracted from a first gas stream at a first temperature and donated to a second gas stream at a second temperature lower than the first temperature by heat conduction through the said heat exchanger plates.  
   
   
       18 . A heat exchanger as claimed in  claim 17 , in which the two gas streams flow in a substantially counter direction along the corrugations of the matrix.  
   
   
       19 . A heat exchanger as claimed in  claim 18 , in which the second gas stream enters through the fluid inlets and leaves through the fluid outlets respectively and the first gas stream passes in between adjacent cells in a counter flow direction.  
   
   
       20 . A heat exchanger as claimed in  claim 17 , in which the first gas stream comprises the exhaust gases of a gas turbine and the second gas stream comprises the compressed air of the said gas turbine prior to its entering the combustion chamber of said turbine.  
   
   
       21 . A heat exchanger as claimed in  claim 1 , in which the cells are substantially flat.  
   
   
       22 . A heat exchanger as claimed in  claim 1 , in which the cells are curved.  
   
   
       23 . A heat exchanger as claimed in  claim 1 , in which the matrix is made from a single spirally wound cell.  
   
   
       24 . A heat exchanger as claimed in  claim 1 , in which the corrugations of the heat exchange portions of the compound plates follow an oscillating path, so that the corrugations define a wave pattern when viewed in a direction normal to the surface of the plate.  
   
   
       25 . A heat exchanger as claimed in  claim 24 , in which the wave pattern of plates in adjacent cells criss-crosses thus allowing greater turbulence in the gas streams and consequently greater heat transfer.  
   
   
       26 . A method of forming a heat exchanger plate comprising the steps of: 
 (a) forming a heat exchange portion, which is of corrugated cross section;    (b) forming a header portion, which is not corrugated;    (c) joining the header portion to the heat exchange portion to form a compound plate.    
   
   
       27 . A method as claimed in  claim 26 , wherein the step (c) comprises crushing the corrugations at an end of the heat exchange portion to the center line of the heat exchange portion, forming a planar surface to which the header portion is joined.  
   
   
       28 . A method as claimed in  claim 26 , wherein the step (b) further comprises forming a second header portion.  
   
   
       29 . A method as claimed in  claim 28 , wherein the step (c) comprises joining a header portion to opposite ends of the heat exchange portion.  
   
   
       30 . A method as claimed in  claim 26 , wherein the portions of the plates are joined together by welding.  
   
   
       31 . A method as claimed in  claim 26 , wherein the portions of the plates are joined together by seam welding.  
   
   
       32 . A method as claimed in  claim 26 , further comprising the step of forming a plurality of holes in the header portion or portions.  
   
   
       33 . A method as claimed in  claim 26 , further comprising the step of forming a plurality of projections on the header portion or portions.  
   
   
       34 . A method as claimed in  claim 33 , wherein the projections are formed in the shape of ribs.  
   
   
       35 . A method as claimed in  claim 34 , wherein the ribs are formed as flow guides, such that fluid flowing past the plate occupies substantially the full extent of the heat exchange portion.